1. Technical Field
The present invention relates to an aqueous ink for inkjet recording, an inkjet recording device, an inkjet printed matter, and an inkjet recording method.
2. Background Art
Since inkjet printers are relatively quiet, enjoy low running costs, and easily capable of printing color images, they are now widely used at home as output device of digital signals.
In recent years, inkjet technologies have been appealing in business field of, for example, display, posters, and signboards.
In such use, since porous recording media have problems with regard to light resistance, water resistance, and abrasion resistance, non-porous recording media such as plastic film are used. Accordingly, ink for such non-porous recording medium has been developed.
For example, as such ink, solvent-based inkjet ink using an organic solvent as a vehicle or ultraviolet-curable inkjet ink using a polymerizable monomer as its main component have been widely used.
However, the solvent-based inkjet ink evaporates a large amount of the solvent into air, which is not preferable in terms of environmental burden. Some ultraviolet curable inkjet ink have skin sensitization potential. In addition, since an ultraviolet ray irradiator built into a printer is expensive, the application field of the solvent-based inkjet is limited.
Considering this background, an aqueous ink for inkjet recording as widely used at home so far is appealing because of its less burden on environment. Therefore, development of an aqueous ink for inkjet recording that can be directly printed on a non-porous substrate (non-porous recording medium) is in progress. For example, such developments are disclosed in JP-2005-220352-A and JP-2011-94082-A.
However, such aqueous ink has disadvantages in general with regard to image quality in comparison with a solvent-based inkjet ink.
First, since ink does not basically penetrate into a non-porous substrate, the ink on the non-porous substrate needs drying quickly. However, since water is contained in the aqueous ink as main solvent and a hydrosoluble organic solvent is added as additive, drying property deteriorates, resulting in poor drying. For this reason, when a recorded recording mediums is placed on another recording medium or rolled up, strike-through, so-called blocking, easily occurs.
In addition, most of the non-porous substrates are extremely glossy. Therefore, ink to demonstrate high gloss is demanded in order not to impair the integrity of printed portions and non-printed portions when printed. However, unlike a solvent-based ink in which a resin is dissolved in ink, particles are fused to form a layer in the case of an aqueous ink for inkjet recording. Therefore the surface of a printed non-porous substrate tends to become rough, thereby losing gloss.